I. Field of the Invention
The present invention relates generally to an extra-corporeal medical device and method to facilitate exchange of catheters and delivery devices during catheter based procedures requiring a plurality of catheters.
II. Related Art
Guidewires are routinely and extensively used in a variety of medical procedures that include the introduction of a catheter into the vascular system of a patient. In many cardiovascular procedures, for example, a guide catheter with a central guidewire advanced through the vascular system until the site to be treated is reached. Thereafter, the initial or guide catheter may be removed and replaced with another over-the-wire (OTW) catheter designed to perform the therapeutic procedure. During such a procedure, it is often necessary to change the catheter while the guidewire remains in place.
Thus, exchanging catheters and delivery devices has become the essence of catheter-based procedures. Catheters vary in diameter from about 0.008 to about 0.087 inches and the length ranges from 70 to 150 cm. Delivery devices include stents and coil delivery systems ranging in diameter from 0.50 to 1 inch and length up to 150 cm.
Currently, as indicated, the vessels of interest are first accessed by small flexible guide catheters. These catheters have limited ability to perform therapeutic procedures and have to be replaced with larger diameter stiffer catheters which lack the structural flexibility and maneuverability required to access tortuous vessel paths as the primary catheter. Once the guide catheter is in position, the exchange length wire has been placed in a desired vascular segment. Once the exchange length wire is in position, the guide catheter is pulled back over the wire.
The exchange length guidewire includes two segments, an intracorporeal segment and an extracorporeal segment. The intracorporeal segment is the portion of the guidewire that resides in the human vascular system during a procedure. The majority of this segment is either covered by a catheter or lying freely in the intravascular compartment. The proximal portion is covered by an insertion sheath or similar device usually placed in the femoral artery. The insertion sheath may contain a Tuohy Buorst device, or the like, to seal the entry into the vascular system. The extracorporeal segment refers to the portion that is outside of the patient's body and exits through the insertion sheath or hub of the catheter.
The extracorporeal proximal portion of the guidewire that protrudes from the vascular system of the patient must be longer than the length of the over-the-wire (OTW) catheter to enable the guidewire to be held when it exits the guidewire lumen of the OTW catheter prior to the distal end of the OTW catheter entering into the vasculature. This enables one to hold the guidewire first at a point distal to the catheter and later at a point proximal to the catheter when the guidewire exits from the proximal end of the guidewire lumen of the OTW catheter. Because of this, the overall length of a guidewire required to advance an OTW catheter over a prepositioned guidewire must be greater than the length of the segment of the guidewire pre-positioned within the vasculature.
The catheter exchange task requires the guidewire to be stabilized manually and the catheter to be replaced to be retracted gently without displacing the wire. The wire/catheter system has to be kept under constant tension in a straight trajectory with no redundancy to avoid displacing the exchange length wire. The insertion sheath through which the catheter and wire are placed also needs to be stabilized during the procedure.
In a typical exchange procedure, once approximately 10-20 cm of the catheter is outside the insertion sheath, one individual (operator #1) continues to move back pulling the catheter while holding the wire stable in increments. Another individual (operator #2) stabilizes the insertion sheath, and activates and reviews the fluoroscopic monitor. Once the catheter is completely out of the insertion sheath, the operator #2 grabs the unsheathed wire, while operator #1 continues to pull the catheter until it is completely removed. Subsequently, the new catheter is advanced on the wire. Operator #1 holds the proximal end of the wire and stabilizes the proximal end of the catheter while it moves forward. Operator #1 must move forward with the advancing catheter to have appropriate control of the wire. The operator #2 pushes the catheter forward through the introducer sheath while activating and reviewing the fluoroscopic monitor until 10-20 cm of the proximal portion of the catheter remain outside the insertion sheath allowing the operator #2 to control both the wire and the catheter. As is apparent, the procedure is cumbersome, requires two operators, and the need for extensive use of a fluoroscope may result in relatively high doses of radiation to a patient.
Thus, it would present a distinct advantage if the exchange of over-the-wire (OTW) catheters and the accompanying delivery devices during catheter-based procedures could be facilitated and simplified and rapidly preformed by a single operator.